In the mobile LTE (Long Term Evolution) networks currently standardized by the 3GPP (3rd Generation Partnership Project), the data to be transmitted (user data and signalling data) over the radio interface are grouped into data blocks, which are processed, e.g. encoded and block-wise transformed, and provided as data frames for the transmission. The frames are then transmitted as a continuous stream on the radio interface. Regarding the downlink direction, for example, in a terminal device the received continuous data signal has to be processed block-wise in order to recover the original data. Specifically, the data samples obtained from the received signal have to be sub-divided into data blocks, e.g. OFDM (Orthogonal Frequency Division Multiplex) symbols which then are processed by an FFT (Fast Fourier Transformation) and are further decoded in order to arrive at the original data blocks, which then are concatenated to form a data output. In the uplink direction, blocks of data symbols have to be encoded and modulated to generate SC-FDMA (Single Carrier Frequency Division Multiple Access) symbols, which then have to be concatenated in an appropriate way to form a continuous signal stream.
In order to achieve synchronization with the serving cell, the terminal has to synchronize with the frame pattern as provided by the radio base station in the downlink and uplink directions. For maintaining the synchronization when moving relative to the base station, the terminal device has to perform timing adjustments for both downlink and uplink.
A technique for synchronizing the mobile terminal with the network thus requires that the timing of the internal or “base-band” processing related to data blocks which have been received or which have to be transmitted must be decoupled to an appropriate degree from the strictly continuous signal stream in time on the radio interface. This decoupling must also enable the performance of timing corrections of the signal stream transmission and reception which are required to conform to the strict timing pattern of the data signal streams on the radio interface. Moreover, a synchronization technique should also allow the reception of signals from neighbouring cells, which typically have a shifted timing pattern in relation to the serving cell.
In GSM systems, data are transmitted on the radio interface in bursts, which are separated by time gaps. These gaps can be used for timing adjustments by the terminal, thus the synchronization of internal processing with the reception/transmission timing does not pose particular problems. Also in W-CDMA (Wideband Code Division Multiple Access) systems, no particular requirements regarding synchronization have to be observed, as there are no dedicated channels which would have to be coordinated in time between different users, i.e. the reception/transmission timing is not very critical. For example, a timing advance correction is not required.